Transient lactose intolerance

Lactose is the natural sugar in milk and many dairy foods. The small intestine normally makes lactase, an enzyme that breaks lactose into smaller sugars for absorption. If the intestinal lining is irritated after an infection or another illness, lactase activity can fall for a while. Unabsorbed lactose then reaches the colon, where bacteria ferment it and draw in water.

This process can produce abdominal pain, bloating, rumbling, wind, or diarrhoea after dairy. The amount that causes symptoms varies, and temporary symptoms do not automatically mean a lifelong dairy restriction is needed. Other conditions can cause similar symptoms, so the pattern and recovery matter.

Keep a simple record of dairy foods, portions, timing, and symptoms. A clinician may suggest reducing lactose for a short period, then gradually testing tolerance as symptoms settle. Lactose-free alternatives can help maintain variety, but check that your overall diet still provides adequate calcium and other nutrients. Nutrition counselling can help if you need a longer restriction. Avoid cutting out many foods without a clear plan.

Arrange assessment if symptoms are severe, persistent, worsening, associated with weight loss, or causing dehydration. Seek prompt care for blood in the stool, black stool, repeated vomiting, fainting, marked weakness, or severe abdominal pain. A clinician may consider infection, coeliac disease, inflammatory bowel disease, or another explanation rather than assuming lactose is responsible.

Ask whether your symptoms fit lactose intolerance, how long a reduction trial should last, and how to reintroduce dairy safely. Discuss whether food intolerance testing is useful and how to protect nutrition if symptoms continue.